问题描述
我在使用 SQLITE3 时遇到问题.
I am have a problem with SQLITE3.
我使用以下 SQL 脚本创建了 2 个表 persons 和 orders:
I have created 2 tables persons and orders using the following SQL script:
sqlite> create table Persons(
P_Id int primary key,
LastName varchar,
FirstName varchar,
Address varchar,
City varchar
);
sqlite> create table Orders(
O_Id int NOT NULL,
OrderNo int NOT NULL,
P_Id int,
PRIMARY KEY (O_Id),
FOREIGN KEY (P_Id) REFERENCES Persons(P_Id)
);
sqlite> insert into Orders values(1,77895,3);
sqlite> select * from Orders;
1|77895|3
sqlite>
即使persons表是空行也可以插入到orders表中.
Even though the persons table is empty rows can be inserted into the orders table.
它没有显示任何错误.
这怎么可能.
推荐答案
在 SQLite 3.x 中，您必须每次连接到 SQLite 数据库时进行以下查询:
In SQLite 3.x, you have to make the following query every time you connect to an SQLite database:
PRAGMA foreign_keys = ON;
否则 SQLite 将忽略所有外键约束.
Otherwise SQLite will ignore all foreign key constraints.
为什么每次都这样?根据文档，向后兼容 SQLite 2.x.
Why every time? Backwards compatibility with SQLite 2.x, according to the the documentation.
在 SQLite 4.x 中，FK 约束将默认启用.
In SQLite 4.x, FK constraints will be enabled by default.
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